1. Field of Invention
This invention relates generally to electric musical instruments, and particularly to an improved mounting base for an input jack on an electric guitar.
2. Prior Art
Electric guitars all employ the use of a 1/4 inch standard phono jack to connect the instrument to an electric amplifier. The female half of the connector mounts on the instrument, typically positioned out of the musician's sight, on the lower, rear side of the instrument. In one method of construction, the jack fastens to the instrument by mounting in a curved plate following the curved surface contour of the guitar body. The curved plate, in ram, fastens to the guitar body. The plate connects to the guitar body with #2 or #3 wood screws. Most guitar bodies are relatively soft woods such as alder, mahogany, basswood, poplar, etc., and these small screws often strip away from the soft wood.
The jack is connected to the plate by use of a nut on the outside of the plate with a backing nut on the inside of the plate. The nuts engage a threaded ferrule of the female jack running through the jack plate. In some cases, just one nut fastens the jack ferrule to the plate. In such case, the length of ferrule not used in mounting must protrude from the guitar as there is no backing nut for adjustment in ferrule position.
Jack plates, stamped into a concave shape are known, for example the Fender.RTM. Stratocaster.RTM. guitar provides a teardrop shape and the Fender.RTM. Telecaster.RTM. guitar provides a cup shaped jack place. (The terms "FENDER.RTM.", STRATOCASTER.RTM., and TELECASTER.RTM. are registered trademarks of FENDER MUSICAL INSTRUMENTS, INC.) The Fender.RTM. Telecaster.RTM. electric guitar has been in production since 1950. It was the first mass produced electric guitar and it spans a whole musical genre. Virtually every major electric guitar manufacturer has a Telecaster.RTM.-style model in production. A 1994 issue of Guitar Player magazine had a Telecaster.RTM.-style guitar review of 32 different models. The Telecaster.RTM. guitar is now more popular than ever.
The jack plate of the Fender.RTM. Telecaster.RTM. guitar mounts to the body of the guitar without using screws. Instead, as described more fully below, it uses a smaller secondary plate that wedges inside the mounting hole of the instrument when the nut on the outside of the jack plate tightens. The smaller secondary plate often works loose during use. With instrument use, any force applied to the wedge, e.g., bending it beyond its original form, loosens the wedge material, which is typically thin and soft. This inherent weakness is made worse by a large hole drilled through the middle to allow the jack ferrule to pass through. This arrangement limits the amount of torque used when tightening the nut on the outside of the jack. If the nut is over-tightened, it is further prone to loosening.
It is common for the nut to be over tightened by musicians finding the nut loose. Once the nut is over tightened, its useful life is near completion. It cannot be successfully tightened again. The most common short term effect of this problem, besides wobbling and rattling, is short circuited signal wires eventually becoming detached from the input jack. As the unhappy musician repeatedly attempts tightening the nut on the jack, the jack rotates inside the mounting hole. This twists the signal wires further together until one or more wires finally break.
A very common event initiating a sequence of destruction, besides over tightening, is stepping on the guitar cord while plugged into the instrument. This pulls on the weak wedge and bends it past center, thus ending the short useful life of the standard Telecaster.RTM. guitar input jack.
A few electric guitars do not use a mounting plate for the jack. Instead, the jack is mounted directly to the guitar body via a hole drilled in the guitar and accepting the jack ferrule. This leaves the guitar body surface around the jack vulnerable to damage from the male jack, as there is no protective plate. In other words, as the musician attempts to insert the male jack it hits and damages the guitar body.
In all mounting cases, a nut on the outside of the jack is employed, leaving the jack protruding from the guitar body, or surrounding surface, at least the thickness of the nut. This not only gives a very small target area, i.e., area accepting the male jack by simply pushing toward the guitar body, but also works to deflect the male input jack away from the hole. The musician blindly searches for the jack hole when attempting to plug-in the signal cord for connection to the amplifier. Once the protrusion of the female jack is located, the musician attempts to guide the 1/4 inch diameter male jack into the 1/4 inch hole of the female jack. This can require several attempts and often leads the musician to flip over the instrument to see the target hole. Also, nuts fastening the jack to the plate are thin and often become loose, due to contact with only two or three threads.
FIGS. 3A, 3B, and 4 illustrate a prior art input jack configuration and mounting hardware. This is the standard unit utilized by the Fender Telecaster.RTM. guitar and others since 1950. Installation of this unit starts with the drilling of a 7/8 inch mounting hole 10. A wedge 15, is pushed into the mounting hole 10. The diagonal measurement of the wedge 15 is slightly more than the 7/8 inch diameter of the mounting hole 10. The wedge 15 is bent inward at the center to shorten it and allow placement in the mounting hole 10 in orientation parallel to the outside of the guitar body 5. The threaded ferrule 20 of the female input jack 25 fits through a hole 30 in the wedge 15 as the input jack 25 passes through the mounting hole 10 from inside the guitar body 5. The threaded ferrule 20 then passes through a hole in the outer cup 35. The outer cup 35 is stamped 0.034 inch thick steel. A nut 40 tightens down against the outer cup 35 and forces the wedge 15 to lodge into the walls of the mounting hole 10 as wedge 15 straightens. If wedge 15 is bent beyond center, it shortens in length, loosens and the whole assembly falls. Unique to the Telecaster.RTM. guitar, a flat area 36 formed on the guitar body 5 in accordance with the input jack 25 location allows the outer cup 35 to rest flush against the guitar body 5.
A second embodiment of prior art input jack configuration and mounting hardware appears in FIGS. 5 and 6. A mounting plate 45 fastens to the guitar body 5 via four #3 or #4 wood screws 50. The mounting plate 45 is curved to match the radius of the guitar body 5. The threaded ferrule 20 of the input jack 25 passes through a hole in the mounting plate 45. A backing nut 41 adjusts the amount of ferrule protruding through the mounting plate 45. The nut 40 is tightened down against the outside of the mounting plate 45.
A third embodiment of prior art input jack and mounting hardware appears in FIGS. 7 and 8. The guitar body 5 is drilled with a hole 48 for clearance of the ferrule 20 of the input jack 25. The ferrule 20 passes through the hole 48 from inside the guitar body 5 and a washer 50 resides under nut 40.
Illustrated in FIGS. 9A-9D show the previously discussed prior art input jack 25 mounting methods and corresponding target area 13. As the male half 55 of the input jack 25 approaches, the musician's goal is to quickly and conveniently connect input jack 25. To achieve this goal, the end of the male half 55 must fall within a 0.049 square inch target area 13. If the male half 55 lands outside the target area 13 (FIG. 9A) the male half 55 wedges between the outer cup 35 and the nut 40. In FIG. 9B, the male half 55 is either stopped at the plate 45 or it slides off the plate 45 and impacts with the guitar body 5. In FIG. 9C, the male half 55 is most likely deflected away from the target area 13 and impact the guitar body 5.
Thus, prior mounting arrangements for electric guitar jacks suffer from a tendency to loosen during use and a tendency to frustrate the musician when inserting the male plug into the female jack. It would be desirable, therefore, to improve both the structural mounting features of an electrical guitar jack while also making more convenient the insertion of the male plug into the electric guitar jack. The subject matter of the present invention addresses these concerns in a jack base for electrical musical instruments.